Technical Field
The invention relates to a semiconductor structure and a manufacturing method thereof, and more particularly to a semiconductor structure including a buried word line and a manufacturing method thereof.
Description of Related Art
In a manufacturing process of a semiconductor device using a buried word line, intersecting isolation structures are formed in a substrate to define active areas. However, during subsequent formation of the buried word line, both a wet cleaning process and a thermal process may expand the isolation structures, leading to size reduction of the active area. Thus, contact area between a contact and the active area is accordingly reduced, leading to an increase in resistance value between the contact and the active area. In this way, when the semiconductor device is applied to a memory, write recovery time of the memory may be increased and an operating speed thereof may be lowered.
In addition, during the formation of the buried word line, a recess is likely to be formed on the isolation structures. Therefore, during subsequent formation of the contact connected to the active area, a conductive material may remain in the recess of the isolation structures, thus causing short circuit between the contacts.